(Based on emails I've sent in the past.)
The best current website for online writing on this and related subjects is Boxes and Arrows:
http://www.boxesandarrows.com
It's primarily about Information Architecture, but that often overlaps with usability. Here are the article categories:
http://www.boxesandarrows.com//archives/cat_index.php
Ones I've bookmarked include an interview with Jakob Nielsen http://www.boxesandarrows.com/archives/002321.php an article about wireframes, http://www.boxesandarrows.com/archives/002808.php an the editors' recommended books, http://www.boxesandarrows.com/archives/003114.php
This is a good resource page of specific practical guidelines: http://www.usability.gov/guidelines/ "This site is designed to provide over 50 of the top Web design and usability guidelines based on emerging research and supporting information in the field."
Also don't forget about discussion lists, where practitioners discuss their day-to-day challenges, ask and give advice. For usability, the most prominent is CHI-WEB: http://www.sigchi.org/web/
All the discussions are archived on the web, searchable, at http://listserv.acm.org/chi-web.html (for example, all my posts.)
This guy (ex-Microsoft) have put together a list of all the best conversation threads here: http://www.uiweb.com/other/chiweb.htm I definitely urge you to read some of these, as it'll give you an idea of the typical challenges the usability person faces.
There is a London-based discussion list, but it is very quiet and largely useless: http://groups.yahoo.com/group/london_usability/
Also on the grass-roots aspect, you should keep an eye on blogs (personal weblogs) of clever people (or companies) with an interest in the subject. They draw your attention to particular examples of good or bad practice, and lively discussions usually ensue. See e.g. http://webword.com/ http://www.37signals.com/svn/ http://crocolyle.blogspot.com/ http://brightlycoloredfood.com/ http://simon.incutio.com/categories/hci/ http://xplane.com/xblog/
...these blogs are by far the best way to keep up with the "buzz" of the industry. Keeping yourself in the know. Finding more information resources. Learning names of companies and people doing it right.
IBM's site include a large section on user-centered design: http://www-3.ibm.com/ibm/easy/eou_ext.nsf/Publish/572 "the IBM Ease of Use Group's guidelines for creating easy-to-use Web interfaces"
Microsoft has a similar resource at http://www.microsoft.com/usability/ ...but it is more hype-oriented.
This page used to be a handy collection of links to information on usability, but as it is no longer maintained it is becoming outdated. Still a good place to search for specific topics though. http://www.usableweb.com/ "collection of links about information architecture, human factors, user interface issues, and usable design specific to the World Wide Web"
All the good authors on the subject typically have websites with further articles or resources. See for example:
Steve Krug http://www.sensible.com/ Alan Cooper http://www.cooper.com/content/insights/newsletters.asp Jakob Nielsen http://www.useit.com/ Lou Rosenfeld (IA) http://louisrosenfeld.com/home/ Bruce Tognazzini http://www.asktog.com/